Upper Ordovician stratigraphy of Southampton Island, Northwest Territories
The middle to late Caradoc Bad Cache Rapids Formation of Southampton Island consists of three "members": a locally present thin siliciclastic unit, overlain by a highly fossiliferous wackestone, capped by a mudstone, all deposited in a broad, shallow shelf setting. This formation is, possi...
| Published in: | Canadian Journal of Earth Sciences |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1991
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/e91-027 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-027 |
| Summary: | The middle to late Caradoc Bad Cache Rapids Formation of Southampton Island consists of three "members": a locally present thin siliciclastic unit, overlain by a highly fossiliferous wackestone, capped by a mudstone, all deposited in a broad, shallow shelf setting. This formation is, possibly unconformably, overlain by the early Ashgill Boas River Formation, comprising a lower carbonate mudstone and an upper oil shale, deposited in a local, shallow subtidal, restricted basin during a transgression. Early to middle Ashgill strata of the Churchill River Formation are made up of a lower unit with coral-bearing wackestone, representing a return to normal marine conditions, and an upper unit of noncoralliferous wackestones, indicating a regional shallowing. The latter is capped by the Sixteen Mile Brook oil shale. The middle to late Ashgill Port Nelson Formation contains evaporite casts and algal laminites, suggesting a sabkha environment. Mound-like structures in this formation may have resulted from solution collapse brought about by the removal of evaporites after lithification. |
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